A door for preventing burglary is usually equipped with a lock and in addition with a door bell so that persons indoors may be warned that somebody is at the door. The inventor had once filed an application, "A BELL LOCK" with Ser. No. 683,360 for a patent in United States, but given it up later. The inventor filed, again in United States, an application of the same title with a different structure which was numbered with Ser. No. 685,491 and granted a patent numbered U.S. Pat. No. 4,577,584. But the structure of said U.S. Pat. No. 4,577,584, whose bell will not work if it is locked from the inside, can not totally function as a bell.
The purpose of this invention is to provide a tubular door lock whose outside knob can be turned around whether it is locked or not, and this lock can function as a bell completely, too.